Improved CRC32Map checking in several ways:

- servers now compute the map in a separate thread
- CRC32Maps are kept in cache for 30 mins
- CRC32Maps requests cannot be used to overflood a server anymore since their number is limited.
- Transfer modules now send keep alive packets to maintain tunnels when asking for a CRC32Map



git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@4661 b45a01b8-16f6-495d-af2f-9b41ad6348cc

libretroshare/src/ft/ftfileprovider.h

@@ -53,12 +53,6 @@ class ftFileProvider
 		//
 		virtual void getAvailabilityMap(CompressedChunkMap& cmap) ;
 
-		// Provides a complete per-chunk CRC32 map to client who want to check their data.
-		// This is derived in ftFileCreator, but returns false, because we can't ensure that unchecked chunks
-		// will provide a CRC32 that is faithful to the original hash.
-		//
-		virtual bool getCRC32Map(CRC32Map& crc_map) ;
-
 		// a ftFileProvider feeds a distant peer. To display what the peers already has, we need to store/read this info.
 		void getClientMap(const std::string& peer_id,CompressedChunkMap& cmap,bool& map_is_too_old) ;
 		void setClientMap(const std::string& peer_id,const CompressedChunkMap& cmap) ;
@@ -66,6 +60,10 @@ class ftFileProvider
 		// Removes inactive peers from the client list. Returns true if all peers have been removed.
 		//
 		bool purgeOldPeers(time_t now,uint32_t max_duration) ;
+
+		const std::string& fileHash() const { return hash ; }
+		const std::string& fileName() const { return file_name ; }
+		uint64_t fileSize() const { return mSize ; }
 	protected:
 		virtual	int initializeFileAttrs(); /* does for both */